Recently, wind turbines have received increased attention as environmentally safe and relatively inexpensive alternative energy sources. With this growing interest, considerable efforts have been made to develop wind turbines that are reliable and efficient.
Generally, a wind turbine includes a rotor having multiple wind turbine blades. The wind turbine blades are elongated airfoils configured to provide rotational forces in response to wind. The rotor is mounted to a housing or nacelle, which is positioned on top of a truss or tubular tower. Utility grade wind turbines (i.e., wind turbines designed to provide electrical power to a utility grid) can have large rotors (e.g., 30 or more meters in length). In addition, the wind turbines are typically mounted on towers that are at least 60 meters in height. Blades on these rotors transform wind energy into a rotational torque or force that drives one or more generators that may be rotationally coupled to the rotor through a gearbox. The gearbox steps up the inherently low rotational speed of the turbine rotor for the generator to efficiently convert mechanical energy to electrical energy, which is fed into a utility grid. In order to provide the efficient conversion of mechanical energy to electrical energy, the wind turbine utilizes a variety of wind turbine components, such as shafts, gearing components, pitch drives, generator components and other components within the wind turbine driven by wind turbine blades.
Wind turbine blades may be very large and typically are fabricated utilizing hand lay-up composite fabrication techniques. For example, one method may infuse two outer shells of glass fiber with resin. Once the two shells have been cured, prefabricated, cured composite shear webs are bonded to a load bearing spar of a first shell of the two shells. The bonding typically takes place utilizing an adhesive, such as epoxy or other suitable adhesive. Once the adhesive bonding the first shell to the shear web has cured, the second shell is attached to the shear web and bonded thereto. Thereafter, the entire assembly is cured to provide a finished wind turbine blade. These methods suffer from the drawback that there is a large number of adhesive joints used to join various components together. These adhesive joints undesirably add weight and complexity to the wind turbine blade and increase time required the fabrication process. In addition, the large number of adhesive joints also precludes the ability to have tight tolerances and junctions, particularly at junctions between the shell and the shear web of the wind turbine blade.
What is needed is an improved method for fabricating wind turbine blades utilizing fewer adhesive joints, providing tighter material tolerances that result in a lighter weight blade that does not suffer from the drawbacks of known methods.